Animal actuated watering valves such as Miniature Animal-Watering Valve, Cross, U.S. Pat. No. 4,006,716, Feb. 8, 1977 have been in use for many years. The Cross valve consists of a housing connected to a water supply source and the valve is operated by the animal moving a lever from side to side within a passage through which the water exits. Many animals have an inborn trait to stuff material into all openings. This trait results in the animal stuffing bedding material, hair or any other available material into the valve opening thus preventing the lever from moving from side to side. Foreign material in the valve can result in the animal cutting off its water supply, or causing the valve to stick in an open position so as to result in a steady stream thereby flooding the cage and in some cases drowning the animal, or the valve may simply leak.
After the experiment is completed and the animal removed, the cages are often washed by a steady stream of high pressure hot water or steam, and this can result in bedding material and other foreign material being forced into the valve opening. If the cage and valve are dried with intense heat, the foreign material inside the valve is baked to a very hard mass.